Grinding head



July 21, 1959 L, STTLER 2,895,266

GRINDING HEAD Filed May 10, 1957 r' 2,895 266 .ICC patented July 211959 GRINDING HEAD Lowell Statler, Bellevue, Ohio Application May 10, 1957, Serial No. 658,333

' 4 claims. (cl. isi- 180) This invention relates to grinding heads of the portable type and particularly of the type designed to be held by hand against a surface, such as the -face of a blackboard, and in particular a grinding head having a circular band of abrading material, such as sandpaper, mounted on a resilient backing with a high vacuum area well in the center and separated from the circular band by a high vacuum seal of sponge rubber, wherein the high vacuum area creates pressure forcing the circular band of abrading material against a lsurface being resurfaced, and in which the head is carried by an arm or bar of a traveling machine by a universal joint whereby with the circular band positioned against the face of a blackboard or the like and rotated at relatively high speed vacuum through the suction hose draws the dust from the head through the hose cooling the grinding element and continuously cleaning the said element and head.

The purpose of this invention is to provide means for resurfacing blackboards and the like without causing excessive dust and also without producing heat in the grinding element.

Grinding heads have been provided in various types and designs and although such heads have used vacuum hoods over the outer surfaces, such hoods remove, only, dust thrown outwardly by the grinding element and do ont draw air for cooling through the granular materials on the face of the grinding element. Furthermore it is difficult, if not impossible, to arrest all of the dust being thrown outwardly by a grinding head with a hood positioned over the head as the dust is thrown outwardly from the head with considerable force.

With these thoughts in mind this invention contemplates a grinding head having a cavity or high vacuum well in the center with a seal around the high vacuum well and with an outer vacuum passage extended through a tubular handle and opening inside of a circular grinding element whereby air is drawn across the face of the grinding element with such velocity that cooling is effected and all dust is removed before the dust has an opportunity of 'escaping into the atmosphere.

The object of this invention is, therefore, to provide a grinding head for resurfacing flat materials in which both dust and heat are removed from the grinding surface by vacuum through a centrally positioned tubular handle.

Another object of the invention is to provide a grinding head for resurfacing blackboards and the like in which a relatively high vacuum area is provided in the center with a low vacuum passage surrounding the high vacuum area and opening around the inner edge of a circular band of abrading material.

A further object of the invention is to provide an improved grinding head for resurfacing blackboards and the like without dust and in which heat is removed by the large velocity of air passing through the grinding element in which the head is of a simple and economical construction.

With these and other objects and advantages in view the invention embodies a circular casing having a circular ring of sponge rubber therein with a similar inner casing having a thin band of sponge rubber providing a high vacuum well in the center and with a circular band of abrading material, such as sandpaper on the face of the sponge rubber band in the outer casing, and a tubular handle with separate connections to the high vacuum well and space around the inner casing and also having rotating means thereon.

Other features and advantages of the invention will appear from the following description taken in connection with the drawing, wherein:

Figure 1 is a front elevational view of the improved grinding head.

Figure 2 is a cross section through the head taken on line 2 2 of Fig. l illustrating the mounting of the head on a tubular handle and showing a universal joint at the base of the head.

Referring now to the drawing wherein like reference characters denote corresponding parts the improved grinding head of this invention includes a sponge rubber circular body 10 having a centrally positioned opening therethrough providing a backing mounted in a circular casing including an outer disc 11 with a flange 12 extended from the peripheral edge, a sponge rubber ring 13 providing a high vacuum seal mounted on an inner disc 14 between an outer flange 15 and an annular band or partition 16, carried by the disc 14, a universal joint 17 between the handle and grinding head, and a pulley 18 by which the head may be rotated with a V-belt or the like.

The disc 11 is provided with a nipple 19 that extends into a sleeve 20, in which the nipple is held by a key 21, and the 11i-pple and sleeve are mounted on a tube 22 that extends from the disc 11 through a sleeve 23 on which the inner race 24 of a ball bearing 25 is positioned. The pulley 18 is also mounted on the sleeve 23 and the upper end of the ysleeve extends into a hub 26 of the universal joint 17.

The outer race 27 of the bah bearing is mounted in a hub 28 of an arm 29 whereby the head is rotatably mounted in the end of the ann. The -pulley 18 is secured tothe sleeve 23 with a key 30 and a similar key 31 secures the hub 26 of the universal joint to the sleeve.

The sleeves or tubes may be -made of metal, plastic, rubber, or other suitable material.

An inner tube 32 extends from the inner disc 14 through the tube 22 providing an area 33 between the outer surface of the tube 32 and the inner surface of the tube 22, the area 33 being in communication with an area 34 between the discs 11 and 14 and extending through the area 34 to a circular area 35 between the ilange 15 and inner edge of the sponge rubber backing 10. The inner casing is supported from the outer casing or disc 11 with bolts 36 having nuts 37 on inner ends thereof and the bolts are provided with spacing elements 38 that retain the discs 11 and 14 in spaced relation.

With the parts assembled as illustrated and described a band of abrading material, such as sandpaper, as indicated by the numeral 39 is secured, such as by a suitable adhesive, to the face of the backing 10 and as the head is rotated with the element 39 grinding the surface 40 of a sheet of material 41, such as a blackboard, the high vacuum area 42 is sealed from the outer vacuum area by the sealing ring 13 whereby air is generally drawn through the center of the tube 32, as indicated by the arrow 43 and as the device operates air is drawn through the particles of sand or other granular material on the element 39, into the area 35 and through the area 34 into the space 33 between the tubes 32 and 22.

The high vacuum area in the center of the head maintained by the seal 13 draws on the center of the head creating pressure on the surrounding parts and holding the abrading element on the backing band against the surface of a blackboard whereby the grinding element is retained in operative relation to a blackboard without producing stresses or strains in the blackboard.

By this means, all dust is drawn through the head and discharged through the tubular handle and by the same means the large volume of air passing across the abrading element reduces the temperature preventing the element being heated by the friction of the element.

It will be understood that modifications, within the scope of the appended claims, may be made in the design and arrangement of the parts without departing from the spirit of the invention.

What is claimed is:

1. In a grinding head, the combination which comprises a disc having a nipple extended from one side and positioned in the center thereof and having a peripheral flange extended from the outer edge and positioned on the side of the disc opposite to that from which the nipple extends, a band of resilient material providing a backing mounted on the disc and positioned against the inner surface of the flange, a layer of material having an abrading surface secured to the face of the resilient backing band, an inner disc having a flange extended from the peripheral edge positioned in the center of the band and spaced from the inner surface thereof, an annular partition mounted on the inner disc, concentric with and spaced from the flange extended from the peripheral edge thereof, a sealing ring of resilient material positioned between the partition and ange of the inner disc provid ing separating means between the high vacuum area in the center of the head and a vacuum passage between the flange of the inner disc and inner surface of the resilient backing, a tubular handle extended from the nipple of the disc on which the resilient backing is positioned, an inner tube extended from the inner disc through the tubular handle extended from the nipple of the disc upon which the resilient backing is positioned, a universal joint through which the tube extended from the nipple passes, and means for rotating the head.

2. A grinding head comprising a circular body having a centrally positioned opening therethrough, a mounting element on which the body is positioned, an outer tube, means for rotatably mounting the mounting element with the circular body thereon on the outer tube, a disc having abrading material on the exposed surface secured to the face of the circular body, a sealing ring positioned in the centrally positioned opening of the circular body, the sealing ring providing a high vacuum chamber in the center of the grinding head, said high vacuum chamber retaining the grinding head against a surface, and an inner tube extended from the high vacuum chamber within the sealing ring through the outer tube, the area surrounding the sealing ring being connected to low vacuum producing means whereby air is drawn across the face of the abrading disc and between the abrading elements thereon.

3. A grinding head comprising a circular body having a centrally positioned opening therethrough, a mounting disc on which the circular body is positioned, an outer tube, a sleeve connecting the mounting disc to the outer tube whereby the mounting disc is rotatably supported, an abrading disc mounted on the exposed surface of the circular body, a sealing ring positioned in the centrally positioned opening of the circular body providing a high Vacuum chamber in the center of the head, said high vacuum chamber retaining the grinding head against a surface, and an inner tube extended from the high vacuum chamber within the sealing ring through the outer tube, the area surrounding the sealing ring being connected to low pressure vacuum through the outer tube whereby air is drawn across the face of the abrading disc and between the abrading elements on the face thereof.

4. In a grinding head, the combination which comprises a circular body having a centrally positioned opening therethrough, a disc on which the circular body is mounted, an abrading surface on the outer face of the circular body, an outer tube, a sleeve extended from the disc on which the circular body is mounted, means for rotatably mounting the sleeve on the outer tube, a sealing ring positioned in the centrally positioned opening of the circular body providing a high vacuum area within the sealing ring for retaining the grinding head against a surface, a disc positioned in the centrally positioned opening of the circular body and on which the sealing ring is mounted, and an inner tube extended from the disc on which the sealing ring is mounted through the outer tube for connection to high vacuum means, the outer tube being connected to low vacuum means whereby a low vacuum area is provided around the outer surface of the sealing ring and air is drawn into the low vacuum area across the face of the abrading surface and through abrading elements thereof carrying dust produced in grinding through the low vacuum area and tube and away from the grinding head.

References Cited in the iile of this patent UNiTED STATES PATENTS 1,582,664 Bennington Apr. 15, 1925 1,800,341 Davies Oct. 19, 1928 2,673,425 Karnell Mar. 30, 1954 

